340 DR. E, DE FRAINE ON THE 
THE SEEDLING. 
The morphology of the seedling and its most important anatomical 
characters have already been described. The transition from stem to root 
structure takes place high up in the hypocotyl and is of Van Tieghem’s 
type III. The cotyledons each contribute one bundle to the hypocotyl 
(cb. 1 and cb, 2, text-fig. 7, 3), almost immediately bifurcation takes place in 
the phloem, the metaxylem separates into two parts, and the half bundles 
thus formed rotate round the protoxylem until the latter is brought into 
the exarch position (text-fig. 7, 4 and 5). The adjacent phloem groups next 
fuse, metaxylem elements are differentiated, and a typical diarch root is 
produced (text-fig. 7, 6). Epicotyledonary strands may or may not be 
present according to the age of the seedling, but they play no essential part 
in the transition. 
HALOCNEMUM STROBILACEUM, Bieb. 
The morphology of this interesting plant kas already been considered at 
some length, in connection with the discussion of the Salicornian foliar 
sheath, so that only a description of its anatomical features will be given 
here. 
The Stem. 
The primary vascular system of the stem is built up of leaf-trace bundles. 
Anomalous secondary thickening, of a type similar to that described for the 
Salicorniea, sets in very early, rapidly producing a thick zone of lignified 
tissue in which the secondary vascular bundles are embedded. The cortical 
region is limited to a few cell-layers, and in the material available there was 
no sign of the aerating cortex so commonly found in the various species of 
Salicornia. The material however consisted only of shoots eut off from the 
bush, so that the bases of the stems were not represented. 
The Leaf. 
In the disposition of the leaf-tips, the free foliar sheath and the adnate 
foliar region, H. strobilaceum bears a closer general resemblance to Salicornia 
glauca than to any other member of the genus, but the segments are even 
shorter than in this species. The general structure of the leaf-tip and sheath 
are such as has been described for the Palicornieze, so that only the features 
characteristic of Halocnemum will be detailed hero. 
At the node one vaseular strand passes out to each leaf, this foliar trace 
branches into three during its passage through the aqueous tissue of the 
sheath, and the two lateral branches curve gradually round the sheath just 
below the palisade tissue (f.t, text-fig. 12, 3). "Transfusion tracheids (t.) 
develop in abundance in the plane at right angles to that of the exit of the two 
